If you compare the egg to a cell, what did you learn about how water moves into or out of a cell

If we compare a cell with an egg there is a major difference between the outer membrane

in case of cell they are bounded by semi permeable membrane  

The semi permeable membrane is a selectively permeable membrane which allows the movement of only solvent molecule and not solute molecules through it.

So water can move into or out of the cell through cell membrane by a special physical process known as osmosis.  

the water will move from a low concentration gradient to high concentration gradient.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2

a is the correct answer